**Introduction**

In this experiment, “measurement of true noon time”, we will be determining whether the true noon or solar time occurs at 12:00 pm, which is a standard time at the riverside during the time ending January and starting February. This experiment is based on the observation when the sun is directly above our heads during the season at different times.

**Aim**

To determine whether the sun lies directly above our head or not during January end and Starting February.

**Theory**

1. When the sun directly lies above our head is termed solar noon or true noon.

2. We hypothesised that the sun during January and February lies directly above our heads during January end and starting February.

**Requirements**

1. A ruler,

2. A table

3. Graph paper

4. Pen

5. Notebook

**Procedure**

**Step 1:** Take a ruler and some graph paper.

**Step 2:** Cover the table with graph paper.

**Step 3:** Take a ruler and place it vertically on the table.

**Step 4:** Measure the position of the ruler on graph paper between 10:30 AM and 3:00 PM.

**Step 5:** Note down the position at every 10 to 15 minutes interval.

**Step 6:** After the experimentation, trace the shadow of the ruler on the graph paper.

**Step 7:** Measure the length of the traced shadow.

**Step 8**: The obtained data indicate the formation of a parabola on joining the end of the lines.

**Step 9:** The shortest line of the shadow coincided with the minimum of a parabola which corresponds to the solar noon or true noontime.

**Step 10:** At two different locations, perform five tests.

**Step 11:** Using a spreadsheet, plot the data.

**Step 12:** To reduce the errors and measurement errors, fit the data using the function of a parabola. This will also help in locating the minimum of a parabola in a precise way.

**Step 13:** Note down your observation.

**Observation**

1. From this experiment, we observed that the true noon during January end and February beginning happen at 12:11 pm in Riverside.

2. The true noon and standard noontime do not happen at the same time during this season.

3. At solar noon, the incident angle (angle made by sunlight and ruler) is the least. This results in the shortest length of the shadow.

4. At noon, we measured the angle of incidence by drawing a right-angle triangle on graph paper with the perpendicular sides constituted by the shadow of the ruler and the length of the ruler.

5. We also find the effect of the refraction of sun rays on the angle of incidence.

**Result**

1. Our hypothesis, in which we assumed that the true noon and standard noontime are different during January ending and February starting.

2. Solar noon does depend on the elevation of the sun.

3. The elevation of the sun depends on the year, time, and geographic latitude of the location.

4. The used principles are statistical fitting, geometry, and physics for making the astronomical measurement of solar noon.

**Precaution**

1. Ruler should not be large.

2. Repeat the experiment at least five times for accurate measurement.

**Conclusion**

In this experiment, we have determined whether the true noon varies according to the geographic location throughout the year.

**Viva Questions With Answers**

**Q.1 What was the aim of your experiment?**

ANS. To determine whether true noon gets affected during January end and starting February.

**Q.2 Are true noon and standard noontime the same?**

ANS. No, true noon depends on the geographical location and can be more than 12:00 pm on the other hand standard noontime is 12:00 pm.

**Q.3 What was the true noontime in your experiment?**

ANS. It was 12:11 PM.

An Indian nuclear physicist, founding director, and professor of physics at the Tata Institute of Fundamental Research.

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